From: SourceForge.net <no...@so...> - 2011-10-01 15:19:02
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Bugs item #3416844, was opened at 2011-10-01 08:19 Message generated for change (Tracker Item Submitted) made by fkrogh You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Solving equations Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Fred Krogh (fkrogh) Assigned to: Nobody/Anonymous (nobody) Summary: Bad result on linear equation solve Initial Comment: (%i1) bfloat(solve(f+.00005=1,f)); rat: replaced -0.99995 by -19998/19999 = -.999949997499875 (%o1) [f = 9.99949997499875b-1] Correct result would be f=9.9995b-1 (or I am really confused on how to use maxima). Environment details are Maxima version: 5.25.1 Maxima build date: 6:25 10/1/2011 Host type: x86_64-pc-linux-gnu Lisp implementation type: SBCL Lisp implementation version: 1.0.45.gentoo-r0 This shakes by confidence in results obtained for the more complicated function I wanted to solve. Thanks, Fred ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 |
From: SourceForge.net <no...@so...> - 2011-10-01 18:53:56
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Bugs item #3416844, was opened at 2011-10-01 11:19 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Solving equations Group: None >Status: Pending >Resolution: Invalid Priority: 5 Private: No Submitted By: Fred Krogh (fkrogh) Assigned to: Nobody/Anonymous (nobody) Summary: Bad result on linear equation solve Initial Comment: (%i1) bfloat(solve(f+.00005=1,f)); rat: replaced -0.99995 by -19998/19999 = -.999949997499875 (%o1) [f = 9.99949997499875b-1] Correct result would be f=9.9995b-1 (or I am really confused on how to use maxima). Environment details are Maxima version: 5.25.1 Maxima build date: 6:25 10/1/2011 Host type: x86_64-pc-linux-gnu Lisp implementation type: SBCL Lisp implementation version: 1.0.45.gentoo-r0 This shakes by confidence in results obtained for the more complicated function I wanted to solve. Thanks, Fred ---------------------------------------------------------------------- >Comment By: Raymond Toy (rtoy) Date: 2011-10-01 14:53 Message: Everything is working as designed. The call to bfloat is on the RESULT of solve, It doesn't magically make every operation a bfloat. There is an issue with solve calling rat to convert -0.99995 to a rational, but that's a different problem having to do with the default value of ratepsilon. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 |
From: SourceForge.net <no...@so...> - 2012-05-03 20:44:20
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Bugs item #3416844, was opened at 2011-10-01 08:19 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Solving equations Group: None >Status: Closed Resolution: Invalid Priority: 5 Private: No Submitted By: Fred Krogh (fkrogh) Assigned to: Nobody/Anonymous (nobody) Summary: Bad result on linear equation solve Initial Comment: (%i1) bfloat(solve(f+.00005=1,f)); rat: replaced -0.99995 by -19998/19999 = -.999949997499875 (%o1) [f = 9.99949997499875b-1] Correct result would be f=9.9995b-1 (or I am really confused on how to use maxima). Environment details are Maxima version: 5.25.1 Maxima build date: 6:25 10/1/2011 Host type: x86_64-pc-linux-gnu Lisp implementation type: SBCL Lisp implementation version: 1.0.45.gentoo-r0 This shakes by confidence in results obtained for the more complicated function I wanted to solve. Thanks, Fred ---------------------------------------------------------------------- >Comment By: Raymond Toy (rtoy) Date: 2012-05-03 13:44 Message: Closing ---------------------------------------------------------------------- Comment By: Raymond Toy (rtoy) Date: 2011-10-01 11:53 Message: Everything is working as designed. The call to bfloat is on the RESULT of solve, It doesn't magically make every operation a bfloat. There is an issue with solve calling rat to convert -0.99995 to a rational, but that's a different problem having to do with the default value of ratepsilon. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3416844&group_id=4933 |